Percentages

A percentage is a ratio of a number to 100. A percentage is expressed using the symbol %.

A percentage is also equivalent to a fraction with denominator 100.

Examples:

To convert a percentage into a decimal, we only have to divide the percentage by 100.

To convert a decimal into a percentage, we have to multiply by 100%.

Examples:

Some percentages are very common and we must know them by heart:

· 100% is the same number.

· 50% is one half of the number.

· 25% is one quarter of the number.

· 20% is one fifth of the number.

· 10% is one tenth of the number.

Exercises:

1.- Complete:

2.- Calculate:

a) 12% of 600

b) 5% of ...... = 150

Solutions: 1.- a) 1/8; 0.125; b) 40%; 0.4; c) 30%; 3/10

2.- a) 72; b) 3000